CMOS-compatible GaN-on-Si HEMTs with cut-off frequency of 210 GHz and high Johnson’s figure-of-merit of 8.8 THz V

GaN-on-Si high electron mobility transistors (HEMTs) with 80 nm gate length fabricated using Si CMOS-compatible Ta/Al ohmic and Ti/Al gate contacts are reported in this work. The device with a source–drain distance (Lsd) of 750 nm exhibited a high cut-off frequency (fT) of 210 GHz. A three-terminal off-state breakdown voltage (BVds) of 46 V and a high Johnson's figure-of-merit (=fT × BVds) of 8.8 THz V have been achieved in a device with Lsd of 1.5 μm. These results show the great potential of GaN-on-Si HEMTs to realize high-performance-to-cost ratio mm-wave devices through mass production using current Si foundries.